Flax decorticator

ABSTRACT

A decorticating device formed in a manner similar to a disc refiner but having pins on the rotating and fixed discs sloped radially and tangentially to facilitate the travel of the flax through the space between the discs as they are relatively rotated, i.e. all the pins slope radially outward, the pins on the rotating disc also slope rearwardly relative to the direction of rotation while those in the fixed disc slope forwardly in the direction of rotation whereby a high throughput together with ample decortication of the fibre is obtainable.

' United States Patent, [191 Altosaar Mar. 25, 1975 4] FLAX DECORTICATOR 2,747,232 5/1956 Armstrong 19/26 ux Heine Altosaar Baie Dude 3,537,142 ll/I97O villavlcenclo 19/..6

Q b C d FOREIGN PATENTS OR APPLICATIONS AssigneeZ Domtar Limited Montreal, Q 855,358 II/l952 Germany 19/82 I Primary Examiner-Dorsey Newton p 1973 Attorney, Agent, or Firm-C. A. Rowley I. N .14 App 0 00 405 57 ABSTRACT [30] Foreign Application Priority Data A decorticating device formed in a manner similar to Canada H I 53498 a disc refiner but having pins on the rotating and fixed discs sloped radially and tangentially to facilitate the [52] U.S. CI. 19/26, 19/83 travel of the flax through the space between the discs [51] Int. Cl D0lb 1/24 as the are relatively'rotated, Le, all the pins slope ra- I Field of Search 19/26, 5 dially outward, the pins on the rotating disc also slope 241/296 rearwardly relative to the direction of rotation while those in the fixed disc slope forwardly in the direction References Cited of rotation whereby a high throughput together with UNITED STATES PATENTS ample decortication of the fibre is obtainable. 2,685.I08 8/1954 Armstrong l9/5 R 9 Claims, 5 Drawing Figures FLAX DECORTICATOR FIELD OF THE INVENTION The present invention relates to a decorticator, more specifically the present invention relates to a disc type decorticating machine for decorticating flax.

DESCRIPTION or THE PRIOR ART Currently used equipment for decorticating flax particularly for incorporation into paper are relatively complex. One of the simpler machines is shown is US. Pat. Nos. 2,983,965 and 3,064,315 issued May 15, 1961 and Nov. 20, 1962 respectively to Schneider, Jr. This equipment uses a hammermill with the flax carried therethrough in an air stream. The hammers do not contact the housing and thus there is no direct impact crushing the fibre against the housing. The equipment is mobile and may be used directly in the field, but is quite expensive and requiresconsiderable horsepower per ton to achieve proper separation.

A simpler device for decorticating flax is shown in a pair of earlier Canadian Patents namely Canadian Pat. Nos. 506,810 issued Oct. 26, 1954 and 536,840 issued Feb. 5, 1967 both to Armstrong resembles a disc type refiner utilizing a special pin arrangement to flex the fibre and cause separation of bast and dross fibres. It is believed that this arrangement has achieved little if any success commercially. It is further believed this limited success is due to the low production rate of the equipment and difficulties encountered in processing flax that is relatively wet.

Stationary commercial equipment is also used for decorticating flax. However, this equipment also is limited in the type of flax that it can handle and in its production rate and it requires relatively high horsepower per ton of flax processed.

It is thus the object of the present invention to provide a relatively simple device for decorticating flax while achieving substantial throughputs and being able to process relatively moist flax.

SUMMARY OF THE INVENTION Broadly, the decorticator of the present invention comprises a pair of surfaces facing each other, a plurality of projections extending from one of said surfaces and a second plurality of projections projecting from the other of said surfaces, means for rotating one of said surfaces relative to the other, said plurality and said second plurality of projections being arranged in overlapping relationship without interfering with one another, each of said projections on said relatively rotated surface sloping rearwardly relative to the direction of rotation and each of said projections on the other surface sloping forwardly in the direction of rotation, all of said projections sloping radially outward relative to the axis of rotation. A central aperture through said other surface forms an inlet to the space between said pair of surfaces and impeller means for drawing air through said space between said pair of surfaces to draw fibres through said space.

BRIEF DESCRIPTION OF THE DRAWINGS Further features, objects and advantages will he evident from the following detailed description of a preferred embodiment of the present invention taken in conjunction with the accompanying drawings in which:

' FIG. 1 is a schematic section through a decorticating disc type refiner incorporating the present invention;

FIG. 2 is a plan view of the fixed plate illustrating the pin arrangement;

FIG. 3 is a view looking in the direction of arrow A, i.e. radially at one of the pins showing the slope of the pin;

FIG. 4' is a view in the direction of arrow, B, i.e. tangent to the disc showing the radial slope of a pin, and

FIG. 5 is a small section looking in the direction of arrow'A illustrating the relative overlap of the pins on the fixed plate and the moving disc and the tangential slope of these pins.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As schematically illustrated in FIG. 1, the basic elements of the invention comprise a rotating disc mounted on a shaft 12 and driven by a motor 14. The

disc 10 is enclosed within a fixed housing 16 which has a stationary plate 18 spaced from and in facing relationship with the working face 20 of the disc 10. An inlet opening 22 is provided through the plate 18 and in the illustrated arrangement a tubular inlet pipe 24 extends from the inlet opening. This tubular pipe 24 is shown tapering toward the inlet opening. An outlet is provided at 25.

The working face 20 of disc 10 is provided with a plurality of projecting pins 26 each of which projects rearwardly of the direction of movement of the disc and radially outward. A second set of pins 28 project from the plate 18 toward the rotating disc 10. These pins 28 slope forwardly in the direction of rotation of the disc 10 from the plate 18 and radially outward. The pins 26 and 28are arranged in concentric circles with the pins 28 interposed between the pins 26 with sufficient clearance to ensure that the pins 26 and 28 do not interfere as the disc 10 is rotated.

As above indicated, the pins do not project prependicular to the faces of the disc l0'or plate 18 but extend at an angle a thereto when viewed in the radial direction as indicated by arrow A in FIG. 2 and as shown in FIG. 3. This angle a will be substantially the same for the pins on the disc 10 and on the plate 18 but will extend in opposite directions. The slope or size of this angle a influences the amount of work done on the fibres as they pass between the disc 10 and plate 18. The smaller the angle a, the smaller the force component applied to the flax tending to cause it to rotate with the disc 10, and thus the less work done on the fibres the smaller the angle a. Preferably, this angle a should be in the range of about 80 to 45. An angle of about 65 has been found to be particularly suitable. This angle has been shown as substantially the same for both the pins 26 and the pins 28 regardless of their position on the disc or plate. If desired, the angle of the pins 26 may be different from the angle of the pins 28 and also the angle may be different depending on the radial location of the pins on the disc or plate.

It is very important that the pins 26 and 28 slope outwardly, i.e. when looking in the tangential direction towards the pin as indicated by arrow B in FIG. 2 that the pin slope outwardly, namely that the base of the pin be closer to the axis of rotation than the tip of the pin. This angle is designated as an angle B as shown in FIG. 4. The angle ,8 should be at the most 88 and preferably should not be less than depending on the radial position of the pin. It will be apparent that the smaller this angle, the greater the spacing between adjacent circumferential rows of pins must be to permit clearance between the pins 26 and 28 as the disc rotates. This in itself imposes some limitation on the size of the angle [3 and vice versa. The angle [3 facilitates the radial movement of the flax through the space between the disc and plate 18, and thus to some extent governs the amount of work applied to the flax, but is a major factor in determining the throughput. In the preferred arrangement, this angle B will be smaller for those rows of pins arranged on the shorter radius circles.

As above indicated, the pins 26 and 28 intermesh by a distance indicated by the letter L in FIG. 5. It is believed for pins having a height H (see FIG. 3) equal to about 1 inch, the overlap or intermeshing of the pins 26 and 28 L should not exceed about one-half inch and may be less than 0, Le. have nointermeshing at all, but if too much clearance is provided, the flax simply will not be worked sufficiently. It has been found that intermeshing of about one-eighth inch is quite satisfactory with pins having a height equal to l inch.

The height H as above indicated is generally about 1 inch. Preferably, this length should not be less than about three-fourths inch and should not exceed about 2 inches. If the height H is too short the throughput will be extremely limited and proper operation probably will not be obtainable, whereas if the pins are too long they will become relatively weak and may be subject easily to being bent.

It is preferred to use substantially cylindrical pins, preferably having pointed tips. The diameter of these pins of course may be varied but it is preferred that they be in the range of about one-eighth to threeeighths inch in diameter.

Referring back to FIG. 1, it will be noted that the disc 10 is provided with paddles 30 on its rear face 32 adjacent its outer periphery. These paddles pump air out of the housing 18 through a tangential outlet not shown. This pumping action draws air in through the inlet 22 and pipe 24 between the discs 10 and the plate 18 and ejects it throughthe tangential outlet not shown. This arrangement moves sufficient air to entrain the flax as it is introduced to the machine. The tapering pipe 24 results in an increase in velocity as the disc 10 is approached which tends to further align the flax as it is introduced to the space between the disc 10 and plate 18. It has been found that by applying an initial velocity to the flax as it contacts the disc 10 there is less tendency for the flax stems to be twisted together than if the flax is simply introduced through the opening 22.

It will be noted that the inlet pipe 24 is at an angle relative to the face of the plate so that the flax has a velocity component in a radial direction as it enters between the disc 10 and plate 18. Preferably the inlet pipe 24 will extend at an angle of between 35 to 65 to the face of the disc 10.

In one specific embodiment of the present invention, a disc 10 having an outermost circle of pins at a radius of 17% inches with 4 further inner rows at 1 inch radial spacing together with a pair of rows at 2 inch spacing cooperated with a fixed plate having its outermost row at l7 inches with three further rows at 1 inch radial spacing and 2 inner rows at 2 inch spacing. The rotating disc was also provided with pins located within the inlet opening 22 to tend to aid in the feeding.

The angle a of all the pins was set at while the angle B was So /2 for those rows spaced 1 inch, and 78 for those rows spaced 2 inches apart. The pins projected approximately 1 inch, i.e. the dimension H was 1 inch for the pins on the disc and on the plate.

With an arrangement as described in the above paragraph, a throughput of about 10 times that obtained when the pins were perpendicular to the axes was obtainable and the flax product so produced was well decorticated.

Modifications may be made without departing from the spirit of the invention as defined in the appended claims.

l claim:

1. A decorticator comprising: a pair of surfaces in face-to-face relationship, a plurality of projections extending from one of said surfaces and a second plurality of projections extending from the other of said pair of surfaces, means for rotating one of said surfaces relative to the other of said surfaces, said plurality and said second plurality of projections being arranged on said surfaces in concentric rows in intermeshing overlapping relationship so that said plurality and said second plurality of projections do not interfere with one another as said surfaces are relatively rotated, each of said plurality of projections on said rotated surface sloping rearwardly relative to said direction of rotation and each of said projections on the other of said surfaces sloping forwardly in the direction of rotation all of said projections sloping radially outwardly relative to the axis of said relative rotation, a central aperture through said other surface concentric with said axis forming an inlet to the space between said surfaces.

2. A decorticator as defined in claim 1 wherein said rearward slope and said. forward slope is at an angle in the range of 80 to 45.

3. A decorticating device as claimed in claim 2 wherein said pins slope radially outward atan angle of 88 to 4. A decorticating device as claimed in claim 3 wherein said pins slope outwardly at different angles depending on their radial spacing from the axis of rotation with those pins a shorter radial distance from said axis of rotation being sloped outwardly at a smaller angle.

5. A decorticator as claimed in claim 1 further comprising an inlet tube connected to said aperture said inlet tube tapering to a smaller diameter as it approaches said aperture.

6. A decorticator as defined in claim 3 further comprising an inlet tube connected to said aperture, said inlet tube extending at an angle of 35 to 65 to said rotated surface whereby material entering said space between said surfaces has a radial component of velocity as it enters said space.

7. A decorticator as claimed in claim 1 further comprising means to induce the flow of air through said central aperture.

8. A decorticator as defined in claim 3 further comprising means to induce the flow of air through said central aperture, and an inlet tube connected to said aperture, said inlet tube extending at an angle at 35 to 65 to said rotated surface.

9. A decorticator as defined in claim 3 further comprising means to induce the flow of air through said central aperture, and an inlet tube connected to said aperture, said inlet tube extending at an angle at 35 to 65 to said rotated surface and tapering to a smaller diameter as it approachessaid aperture. 

1. A decorticator comprising: a pair of surfaces in face-to-face relationship, a plurality of projections extending from one of said surfaces and a second plurality of projections extending from the other of said pair of surfaces, means for rotating one of said surfaces relative to the other of said surfaces, said plurality and said second plurality of projections being arranged on said surfaces in concentric rows in intermeshing overlapping relationship so that said plurality and said second plurality of projections do not interfere with one another as said surfaces are relatively rotated, each of said plurality of projections on said rotated surface sloping rearwardly relative to said direction of rotation and each of said projections on the other of said surfaces sloping forwardly in the direction of rotation all of said projections sloping radially outwardly relative to the axis of said relative rotation, a central aperture through said other surface concentric with said axis forming an inlet to the space between said surfaces.
 2. A decorticator as defined in claim 1 wherein said rearward slope and said forward slope is at an angle in the range of 80* to 45* .
 3. A decorticating device as claimed in claim 2 wherein said pins slope radially outward at an angle of 88* to 70* .
 4. A decorticating device as claimed in claim 3 wherein said pins slope outwardly at different angles depending on their radial spacing from the axis of rotation with those pins a shorter radial distance from said axis of rotation being sloped outwardly at a smaller angle.
 5. A decorticator as claimed in claim 1 further comprising an inlet tube connected to said aperture said inlet tube tapering to a smaller diameter as it approaches said aperture.
 6. A decorticator as defined in claim 3 further comprising an inlet tube connected to said aperture, said inlet tube extending at an angle of 35* to 65* to said rotated surface whereby material entering said space between said surfaces has a radial component of velocity as it enters said space.
 7. A decorticator as claimed in claim 1 further comprising means to induce the flow of air through said central aperture.
 8. A decorticator as defined in claim 3 further comprising means to induce the flow of air through said central aperture, and an inlet tube connected to said aperture, said inlet tube extending at an angle at 35* to 65* to said rotated surface.
 9. A decorticator as defined in claim 3 further comprising means to induce the flow of air through said central aperture, and an inlet tube connected to said aperture, said inlet tube extending at an angle at 35* to 65* to said rotated surface and tapering to a smaller diameter as it approaches said aperture. 